This invention relates generally to knit hosiery, and more particularly to a circularly-knit sock with a targeted compression zone. In various exemplary applications, the compression zone of the present sock may function alone or in combination with other features to “lock” the sock foot in position on the wearer during use. In addition to improved fit and comfort, the present sock may enhance a runner's proprioception, kinesthetic awareness, stamina or endurance, and overall performance.